Past Perfect
Use
1) Together with the Simple Past
Mary had read the book before she watched a film.
2) the past equivalent of the Present Perfect
He had played hockey.
Signal words
no unambiguous ones
Form
had + past participle
Examples
Affirmative sentences:
I had played hockey.I'd played hockey.
You had played hockey.You'd played hockey.
Negative sentences:
I had not played hockey.I'd not played hockey.I hadn't played hockey.
You had not played hockey.You'd not played hockey.You hadn't played hockey.
Questions:
Had you played hockey?